Thanks for detailed explanation,no report names need to be shown,in the chart,top 25 group can be shown as Top25 with one color[this explains how much percentage top 25 occupied],Top50 with another color etc for a month in one line bar in the chart.

I saw your other post on Top N pie as below ,I am looking for same but instead of each customer,my case here is I need Top10 grouped into one ,Top20 grouped into one,etc and their percentage.We can represent in line chart as above or pie also looks fine.

In which case, as the set is created against customer (or customer + month) the set allocation of In/Out is returned at a row level, and so can be used to create a dimension.

So for Top 10/Rest it would be

IF [Top 10] THEN 'Top 10' ELSE 'Rest' END

btw [Top 10] here is just the set...they equate to True (in) or False (out) so no need for any further statements.

You can then bring this dimension onto colour and you'll get %age (of whatever measure) of Top 10 and the rest....you can equally just put the set onto the colour and change the set alias as Shin has showed.

I'm a little confused on your actual requirement, as won't the Top 20 include the Top 10?...however ignoring this you can do like

IF [Top 10] THEN 'Top 10'

ELSEIF [Top 20] THEN 'Top 20'

ELSE 'Rest'

END

As an IF statement exits once a condition is found you'll actually get...

No problem....I feel a bit like Gary Lineker* here, after your excellent and detailed explanation!

*for those not versed in the depressing affair that is our England soccer team...Gary Lineker was a 'goal-hanging' striker in the 1990s...the rest of the team did all the hard work, and then he'd pop up, knock the ball in the goal and take all the glory!!